The assessment of optical hazards in recent years has led to the recognition of the possible hazards to the retina associated with blue light. Generally speaking blue light has a wavelength in the range of about 400-500 nm. If the blue light hazard is a real threat to vision, then the UV/visible transmission characteristics of ophthalmic lenses, and intraocular lenses (IOLs) in particular, should be modified to provide adequate protection from blue light hazards encountered in the environment.
In the ambient environment, solar radiation is the primary vision hazard. The sun freely emits UV, visible and IR radiation much of which is absorbed by the atmosphere. The solar radiation that is transmitted through the atmosphere and reaches the earth's surface consists of UV-B radiation (230-300 nm), near UV or UV-A radiation (300-400 nm), visible light (400-700 nm) and near IR radiation (700-1400 nm). The ocular media of man in its normal, healthy state freely transmits near IR and most of the visible spectrum to the retina. UV-B radiation is, however, absorbed by the cornea and does not reach the retina. UV-A and the blue portion of the visible spectrum can be absorbed by the crystalline lens of the eye depending upon the person's age.
The human crystalline lens changes its UV and visible transmission characteristics as it ages. In infancy the human lens will freely transmit near UV and visible light above 300 nm, but with further aging the action of UV radiation from the environment causes the production of yellow pigments, called fluorogens, within the lens. By approximately the age of 54 the lens will not significantly transmit light below 400 nm and the transmission of light between 400 and 500 nm is greatly diminished. As the lens ages it continuously develops a yellow color, increasing its capacity to filter out near UV violet, and blue light.
Currently, IOLs capable of blocking UV and blue light to varying degrees use yellow dyes. However, there are some major drawbacks with such IOLs:                1. Patients with yellow dye-containing IOLs experience reduced vision quality in dim light conditions. The yellow dyes used in current IOLs absorb light over of a relatively large band of wavelengths and a higher concentration is needed to achieve adequate blue light filtration. This causes a shift of absorption from the UV-violet-blue (200-420 nm) to the green region (420-470 nm).        2. The presence of blue light blocking chromophore in e.g., IOLs, reduces contrast sensitivity in some cases.        
Due to their intense yellow color (which the presence of blue light chromophores imparts to IOLs), blue light blocking chromophores in IOLs and other ophthalmic devices may interfere with color perception.